Paul Thomas wrote:
> I've been using the mcp251x driver, and I'm getting a "write: No buffer
> space available" error. That is what cansend prints after I get into this
> state. I have a user space program that is reading and writing about 20 time
> a second.
>
> I see this with both the work-queues and threaded interrupt version. In the
> threaded interrupt version unloading and reloading the mcp251x module fixes
> the problem. In the work-queues version just disconnecting the can device
> and re-connecting it fixes it.
>
> Is there some way to purge/flush the buffer? Is there some other work around
> sort of reloading the module?
It may happen that the TX buffer space is exhausted, especially if you
send many messages without delay (in a loop). The driver should handle
the errno appropriately:
retry:
ret = write(s, &frame, sizeof(struct can_frame));
if (ret < 0) {
if (errno == ENOBUFS) {
sched_yield();
goto retry;
} else {
perror("write failed");
goto failure;
}
Search for ENOBUFS in the can-utils "cangen.c" or "canfdtest.c". The TX
queue length can be increased with "ip link can0 txqueuelen <size> ...".
Wolfgang.
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